<template>
  <div id="app">
    <div>
      <p>请选择你要购买的书籍</p>
      <ul>
        <li v-for="(item, index) in arr" :key="index">
          {{ item.name }}
          <button @click="add(index)">买书</button>
        </li>
      </ul>
      <table border="1" width="500" cellspacing="0">
        <tr>
          <th>序号</th>
          <th>书名</th>
          <th>单价</th>
          <th>数量</th>
          <th>合计</th>
        </tr>
        <tr v-for="(item, index) in arr" :key="index">
          <th>{{ index + 1 }}</th>
          <th>{{ item.name }}</th>
          <th>{{ item.price }}</th>
          <th>{{ item.count }}</th>
          <th>{{ item.count * item.price }}</th>
        </tr>
      </table>
      <p>总价格为:{{ total }}</p>
    </div>
  </div>
</template>

<script>
export default {
  name: "App",
  data() {
    return {
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
    };
  },
  methods: {
    add(i) {
      this.arr[i].count += 1;
    },
  },
  computed: {
    total() {
      return this.arr.reduce((t, c) => t + c.price*c.count, 0);
    },
  },
};
</script>

<style>
</style>